mac: Use -fstack-protector-strong instead of -fstack-protector-all.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 3357 matching lines @@
           }],
           ['OS=="linux" and target_arch!="ia32" and disable_glibcxx_debug==0', {
             # Enable libstdc++ debugging facilities to help catch problems
             # early, see http://crbug.com/65151 .
             # TODO(phajdan.jr): Should we enable this for all of POSIX?
             'defines': ['_GLIBCXX_DEBUG=1',],
           }],
           ['release_valgrind_build==0', {
             'xcode_settings': {
               'OTHER_CFLAGS': [
-                '-fstack-protector-all',  # Implies -fstack-protector
+                '-fstack-protector-strong',  # Implies -fstack-protector
               ],
             },
           }],
         ],
       },
       'Release_Base': {
         'abstract': 1,
         'defines': [
           'NDEBUG',
         ],
@@ skipping 197 matching lines @@
         'ldflags': [
           '-Wl,-z,defs',
         ],
       },
     }],
     ['os_posix==1 and chromeos==0', {
       # Chrome OS enables -fstack-protector-strong via its build wrapper,
       # and we want to avoid overriding this, so stack-protector is only
       # enabled when not building on Chrome OS.
       # TODO(phajdan.jr): Use -fstack-protector-strong when our gcc
-      # supports it.
+      # supports it.  See also https://crbug.com/533294
       'target_defaults': {
         'cflags': [
           '-fstack-protector',
           '--param=ssp-buffer-size=4',
         ],
       },
     }],
     ['os_posix==1 and OS=="linux"', {
       'defines': [
         '_LARGEFILE_SOURCE',
@@ skipping 2719 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }